Be prudent of ketamine in treating resistant depression in patients with cancer.

Chun Yang, M.D., Zhi-qiang Zhou, M.D., Ph.D., and Jian-jun Yang, M.D., Ph.D.Dear Editor:Pain, suffering, hopelessness, loneliness, and fear of death arethe main contributing risk factors to the development of depressionin patients with cancer.1 Antidepressants are intendedto improve patients’ mood status and alleviate depression.Unfortunately, conventional antidepressants, such as imipramineand fluoxetine, cannot effectively ameliorate the symptomsof refractory depression in some patients with cancer.Ketamine as a classic anesthetic agent has often been usedduring anesthesia for pediatric operations. Latest data havesuggested that a subanesthetic dose of ketamine has robustand rapid therapeutic effects in the treatment of depression,especially for patients who are resistant to conventional antidepressants.1–3 Thus, ketamine has the potential to be aninnovative antidepressant, which is different from the conventionalantidepressants that exert antidepressant effects viathe inhibition of the monoamine transmitter transporter inpresynaptic membranes.However, a recent study has revealed that the underlyingmechanism of the antidepressant effects of ketamine is principallydue to the up-regulation of mammalian target of rapamycin(mTOR).4 This study suggests that the signalingpathways of rapid activation of mTOR is a novel strategy forthe rational design of a fast-acting antidepressant.4 However,the up-regulated mTOR may cause the acceleration of tumorgrowth.5 Therefore, further studies involved in patient prognosisare needed to investigate whether ketamine is suitablefor the treatment of refractory depression in patients withcancer.